An international team of archaeologists has found evidence of complex symbolic and technological behaviors at Ga-Mohana Hill in the Northern Cape, South Africa dating back to 105,000 years ago — the same age when those behaviors occurred on the coast. The discovery challenges the idea that the origins of our species were linked to coastal environments.
The archaeological record of Africa provides the earliest evidence for the emergence of the complex behaviors that characterize Homo sapiens.
The coastal setting of many Late Pleistocene sites and the abundant shellfish remains recovered from them have led to a dominant narrative in which modern human origins in southern Africa are tied to the coast and marine resources.
However, Late Pleistocene sites with good preservation and robust chronologies are rare in the interior of southern Africa, and the coastal hypothesis therefore remained untested, until now.
“Archaeological evidence for early Homo sapiens has been largely discovered at coastal sites in South Africa, supporting the idea that our origins were linked to coastal environments,” said Dr. Jayne Wilkins, an archaeologist in the Australian Research Centre for Human Evolution at Griffith University.
“There have been very few well-preserved, datable archaeological sites in the interior of southern Africa that can tell us about Homo sapiens’ origins away from the coast.”
“A rockshelter on Ga-Mohana Hill that stands above an expansive savannah in the Kalahari is one such site.”
Ga-Mohana Hill is located in the southern Kalahari Basin, 12 km north-west of Kuruman in South Africa and over 600 km from the nearest modern coastline.
The name Kalahari is derived from the Tswana word Kgala, meaning ‘great thirst.’ However, ancient proof of abundant water on the landscape is evident from striking tufa formations.
“We’re showing a record of water in the rocks that not only matches the archaeological record but also provides evidence of a crucial resource for the people living at Ga-Mohana,” said Jessica von der Meden, a Ph.D. candidate in the Human Evolution Research Institute and the Department of Geological Sciences at the University of Cape Town.
“This is a story of water in what we know now as a dry landscape, and of adaptable people who exploited the landscape to not only survive but to thrive,” said Dr. Robyn Pickering, director of the Human Evolution Research Institute (HERI) at the University of Cape Town.
Dr. Wilkins and colleagues excavated three areas of Ga-Mohana Hill North Rockshelter, the largest of two main shelters and several small overhangs that occur within the dolomitic Gamohaan Formation.
They unearthed 22 white calcite crystals and fragments of ostrich eggshell, thought be used as water containers, from deposits dated to 105,000 years ago.
“Our analysis indicates that the crystals were not introduced into the deposits via natural processes, but were deliberately collected objects likely linked to spiritual beliefs and ritual,” Dr. Wilkins said.
“The crystals point towards spiritual or cultural use of the shelter 105,000 years ago. This is remarkable considering that site continues to be used to practice ritual activities today,” added Dr. Sechaba Maape, an archaeologist at the University of the Witwatersrand.
The chronology of Ga-Mohana North Rockshelter was determined by the team using luminescence dating.
“This technique measures natural light signals that accumulate over time in sedimentary quartz and feldspar grains,” said Dr. Michael Meyer, a researcher in the Department of Geology at the University of Innsbruck.
“You can think about each grain as a miniaturized clock, from which we can read out this natural light or luminescence signal, giving us the age of the archaeological sediment layers.”
The researchers were delighted to discover that the assemblage of human-collected crystals and ostrich eggshell fragments at Ga-Mohana Hill were significantly older than that reported in interior environments elsewhere.
“At coastal sites, the earliest evidence for these kinds of behavior date to about the same time, 105,000 years ago,” Dr. Wilkins said.
“This suggests that early humans in the Kalahari were no less innovative than those on the coast.”